Artisans in Mesopotamia began deliberately alloying copper with tin at approximately a 10:1 ratio to produce bronze, a material harder and more durable than either parent metal. Archaeological evidence from multiple sites documents this practice spreading across the region around 3000 BCE. The intentional manipulation of two substances to yield a third with distinct properties represents an early applied understanding of material chemistry, with consequences for toolmaking, weaponry, and trade networks across the ancient Near East.